Episode 1

S3, E1: In the dead of night, out at sea, a Syrian boy (Farid) and two other stowaways cower on the deck of a trawler. Terrified, the refugee children watch as a gas-masked man boards their boat, pours petrol over it and sets it alight. When Karl and BB find a toy car among the blackened debris, Karl’s determined to find the children, despite new boss Winnie's directive that it is the French police’s problem. Karl arrives in Calais to find Elise has given up her role as commander to smarmy Astor Chaput... In the Eurotunnel, an engineer is sent to fix faulty lights, but finds herself engulfed by a tsunami of frenzied rats while, on the Kent coast, Helena Carver goes to wake up her children, only to find the refugee children in their beds. Elise starts to piece together the child swap and the plague of rats and the story that links them. The Carver children have vanished, but in Karl and Elise's increasingly desperate search, they find another boy: Charlie Moreau. Eight years ago, Elise and Olivier convicted Charlie’s father Jacques for the boy’s murder. How did they get it so wrong?